The invention relates to communication network and communication system, and in particular to the generation of signal modulation in a communication system.
In some current communication networks, e.g. in a WCDMA (Wideband Code Division Multiple Access) system, the normal downlink (and uplink) modulation is QPSK (Quadrature Phase Shift Keying). A service HSDPA (High Speed Downlink Packet Access) introduces new modulation schemes. 8PSK (Phase Shift Keying), 16QAM and 64QAM modulations (QAM=Quadrature Amplitude Modulation) are proposals in standardization. A problem is how to generate these higher order constellations with existing (on HW) QPSK modulators.